Injection pump



Nov. 10, 1942.

J. MERCIER INJECTION PUMP Filed May 8. 1941 6 Sheets-Sheet l Nov. 10, 1942. J. MERCIER INJECTION PUMP Filed May 8, 1941 s Sheets-Sheet 2 Filed May 8, 1941 6 Sheets-Sheet 3 J. MERCIER Nov. 10, 1942.

6 Sheets-Sheet 4 I Nov. 10, 1942. J. MERCI ER INJECTION PUMP v Filed May 8, 1941 6 Sheets-Sheet 5 Nov. 10, 1942,

r J. MERCIER I INJECTION PUMP 6 Sheets-Sheet 6 Filed May 8, 1941 Patented Nov. 10, 1942 UNITED STATES PATENT OFFICE INJECTION PUMP Jean Mercier, Paris, France Application May a, 1941, Serial No. 392,579

13 Claims.

The present invention relates to fuel injection P p An object of the invention is to provide a pump of this type in which leakage around the piston 1 during the injection stroke is practically eliminated.

Another object of the invention is to provide a fuel injection pump in which the piston is already travelling with a high velocity when the injection of fuel is started, that is to say discharge valve opens,

Still another object of the invention is to provide an injection pump in which the discharge when the pipe is opened as suddenly as possible, which corresponds to a very sharp rise of the pressure in the pump barrel.

Still another object of the invention is to pro-- vide a pump of the type above mentioned with means for accurately controlling the end of the injection, said .end being also as sudden as possible.

With these, and other, objects in view, according to an essential feature of the invention, I

provide, in permanent communication with the portion of the pump barrel located between the piston and the dischargevalve', a chamber of variable volume and means for. controlling the volume of said chamber so as to-permit its free increase during at least one portion of the stroke 4 of the piston and, on the contrary, to prevent said increase during another portion of said stroke.

Other features of the present invention will result from the following detailed description of some specific embodiments thereof.

Preferred embodiments of the present invention will be hereinafter described, with reference to theacconipanying drawings, given merely by nism S;

Fig. 5 is a partial view showing said mechanism from the same view point as in Fig. 3, but

after it has snapped open;

Fig. 6 is a diagrammatic axial section, similar to Figs. 1 and 3, showing a modification of the embodiment of Fig. 3;

Fig. 7 is a similar view, showing still another embodiment,

As shown by the drawings, the pump according to the invention includes a pump body I provided with a cylindrical bore 2 forming the pump barrel. In this pump barrel .2- is slidably mounted the piston 3 of the pump, actuated in any suitable manner.

For instance, in the embodiment shown by Figs. 1 and 2, the lower end of piston 3 cooperates with a roller 6|, carried bva lever 62 pivoted at 63. This roller 6| is further subjected tothe action of a push-piece 64, urged upwardly by a spring 55 interposed between said push-piece and the bottom of casing 60, which is rigid with frame I. r

Piston 3 is further urged in the downward di- --the pump barrel 2. In this chamber II! is slidably mounted a piston I I.

An adjustable stop piece I2 is carried by the frame I of the system so that it can occupy any desired position .(within given limits) along the common axis of chamber III and piston. For instance this piece I2 carries a worm I3 in mesh with a rack I4, guidedwith respect to body I.

I can thus control the point at which the downward stroke of piston I I is suddenly stopped by its contact with piece I2.

In order to ensure the return of piston II to its upper position, a return spring I5 is interposed ,between the upper end of piston II, and a plunger I6 fixed to the frame of the pump through a nut I'I.

This pump will workin the following manner: The downward stroke of piston 3. takes place under the action of'spring 5 when roller 6| is I moving downwardly as the resultoi the motion imparted to lever 62 by cam 4, and against the action of spring 65.

Duringthis downward stroke-piston 3 draws in liquid intobarrel 2 through conduit 6 and port 9.

Then roller 68 comes to'run beyond the point 4 of the outline of cam '4, which permits lever 62 to pivot upwardly under the effect of pushpiece 64 and spring 65. This upward pivoting movement of lever 62 corresponds to an upward stroke of piston 3.

In the course of this upward stroke, the upper edge of piston 3 comes to the level of the upper edge of port 9 (position shown by Fig. ,l). The portion of the pump barrel 2 above piston 3, and the chamber l0, above piston I I, which communicates with said pump barrel, are now filled with liquid which, in the course of the remainder of the upward stroke of piston 3, can escape to the outside only through discharge pipe 6, past valve 1, this discharge taking place when the pressure in barrel 2 suddenly rises and overcomes the resistance of spring loaded valves 1.

But, for a certain time after piston 3 has moved upwardly beyond the position illustrated by Fig. 1, the pressure in barrel 2 does not rise, because piston II is simultaneously moving downwardly in cylinder l0 so that the total volume of chambers 2 and I0 does not tend todecrease.

Piston 3 thus comes to the position illustrated by Fi 2, 'where it has considerably overlapped port 9, and which corresponds to the lower end of piston striking stop piece l2 and bein suddenly immobilized by its contact with said top piece.

A piston 3, under the action of cam 4, keeps moving at high speed, there is a very sudden rise of pressure in chamber 2, which causes valve 1 to open practically instantaneously, whereby injection starts in a very sharp manner.

As the top edge of piston 3 is now at a considerable distance beyond the top edge of port 9, no danger of liquid leaking back to said port toward the inlet conduit 3 can occur.

The end of the injection takes place when an abutment 69, provided at the lower end of piston 3 comes into contact with a shoulder Ill, provided on casing 60. Then, as roller 68 has now run along cam I beyond point 4', lever 62 moves downwardly and piston 3 follows its movement-under.

the action of spring 5.

The annular groove 3 corresponding to the inlet port in the pump barrel is in communication with another annular groove l3 provided in the inner wall of cylindrical bore III, so that, if liquidleaks along said wall, it'returns to the inletcircuit, and further prevents the inflow of air during the suction stroke.

According to an important feature of the invention, I can determine the end of the injection by controlling the displacement of piston l l For instance, this piston being supposed to be fixed in position during the injection, is suddenly allowed to move freely when it is desired to stop the injection, so that the pressure drop thus produced in the pump barrel causes valve 1 to close.

Embodiments of mechanisms adapted to pro:- duce this operation are shown by Figs. 3 to 7.

In these embodiments of pumps according to the invention, the beginning of the cycle of operation is supposed to be the same as above described with reference to Flg. 1.

For instance, in the embodiment of Figs. 3 to 5, the stopping of the downward movement of piston II is produced by the contact of a rod, 20, carried Stop piece 2| can occupy either of two positions, to wit its upper position, shown by Fig. 3, in which it is held by the snap action mechanism S, interposed between fixed spindle A and p ece a position which corresponds to said branches being in line with each other and thus holding piece 2| in its upper position) by respective abutments bearing against each other along line 28. Branch 24 is pivoted to piece 2| about spindle 26, while branch 25 is pivoted about spindle A. When the above mentioned abutments of branches 2| and 2 5 are applied against each other (along line 28), spindle 21 is located in the plane of spindles 26 and A, and the whole is resiliently held in this position by a spring 23 interposed between an element of body and a lever 30 carried by branch 25. It will be readily understood that as soon as the contact of the shoulder 22 of piston 3 with projection 23, carried by branch 25, has caused said branchto pivot so that spindle 21 is now located on the right hand side of the plane of spindles 26 and A, the knuckle joint is broken and snaps open, the downward thrust on piece 2| being opposed merely by the action of spring 23, which is very small with respect to thrust.

Therefore piston II is suddenly allowed to move downwardly, the pressure drops in barrel 2, valve 1 closes and the injection is suddenly stopped.

.The point at which this action takes place can be determined at will by making spindle A adiustable vertically with respect to the pump body In this case, a vertical displacement of spindle A modifies both the beginning and the end of the injection period. In order to permit of modifying only the end of this period, the shoulder 22 of the main piston 3 is made of helical shape, so that, by turning piston 3 about its axis, I can vary the time at which projection 23 is struck by said shoulder 22';

In the modiflca on illustrated by Fig. 6, piston is.stopped in i downward movement by the contact or its bevelled lower edge 36 with balls 33 mounted in radial holes 31 provided in a piece 33 adjustably fixed with respect to the body of the pump.

A movable piece, movable vertically together withpiston 3, is provided with an annular space 63 into" which 36 can penetrate when said,

recesses come opposite holes 31.

In the course of this radial movement, said balls come to be tangent to the cylindrical wall of an annular recess 4| providedin piece 38 and corresponding in shape and size to the outer cylindrical wall of piston Therefore, this piston can now freely move down in said space II, which, as above explained, immediately produces the end of the injection.

Finally, in the embodiment of Fig. 7, the stop piece 5| against which piston ll strikes for producing the beginning of the injection has its vertical position determined by a rgller M carriedby a lever 43, pivoted at 42 and controlled by a' cam 45. This cam is circular over-a portion of its periphery, whereby roller 44, and consequently tion, so that piston II can slide freely in the downward direction and the pump injection is stopped. A spring 49 keeps lever 43 applied against cam 45. Gain 45 also acts on a lever'4'l, pivoted at 46 and the other end of which is fitted -'with a roller 48 which controls the vertical displacements of the main piston 3. The latteris urged in the downward direction by a spring 52. The position of point 42, about which lever 43 is pivoted can be adjusted from the outside by means of hand wheel 53.

It will be noted that the movement of roller 44, which constitutes the movable abutment which is to coact with auxiliary piston II, is produced by a cam 45 which imperatively pushes lever 43 downwardly when said ,auxiliary piston is 'to be released. At first sight it would seem simpler to obtain this movement by means of a cam which would keep lever 43 in an upward position and which, at thedesired time, would allow this lever to pivot downwardly. But the disadvantage of this system would lie in the necessity of employing a cam having an outline including first a circular portion and then a portion of decreasing-diameter forming an external angle with the circular portion.

On the contrary, in the device according to ,the invention,'cam 4.5 is so shaped that after a circular portion there is a portion projecting with respect thereto, the whole forming an internal angle at a. Now this arrangement is particularly advantageous because the sudden downward displacement of the roller carried by the end of roller '43, which runs on cam 45, when this last mentioned roller comes unto the noncircular portion of said cam 45, corresponds exactly to the outline of the cam. As a matter of fact, in an arrangement of this kind (in which the cam outline,forms an internal angle), the

' center of the last mentioned roller describes a curve which is exactly parallel to the outline of the cam andwhich, therefore; reproduces the angle in question, whereas, if the cam made an external angle, the trajectory of the center of said roller would include two curvilinear elements parallel ,to the corresponding elements of the outline of the cam which constitutes the sides of this external angle, but joined to each,other by a circular are instead of forming a sharp angle which would prevent the sudden movement of sharp angle provided in the cam outline.

In a general manner, while I have, in the above description, disclosed what I deem to be practical and eflicient embodiments of the present invention, it should be well understood that I do not wish'to be limited thereto as theremight be changes made in the arrangement, disposition and form of the parts without departing from the principle of the present invention as comprehended within the scope of the appended claims.

What I claim is:

1. An injection pump which comprises, in comthe lever, which is to be. obtained owing to thebination, a pump barrel,.liquid inlet means connected to said pump barrel,"a piston movable in said pump barrel, a spring loaded discha ge valve connected with said pump barrel, a cylinder in permanent communication with the portion of said pump barrel between said piston and said injection.

- with respect. to its cylinder so as tokeep thev volume of said chamber constant, during the injection and meansfor suddenly releasing said second piston to permit free increase of the volume of said chamber, whereby the pressure drops suddenly in said 2. An injection pump which comprises, in combination, a pump barrel, liquid inlet means connected to said pump barrel, a piston movable in said pump barrel, a spring loaded discharge valve connected with said pump barrel, a cylinder in permanent communication with the portion of said pump barrel between said piston and said discharge valve, a piston slidable in said cylinder, so as to form, in said cylinder, a variable volume chamber communicating with said portion of the pump barrel, means for locking said second piston with respect to its cylinder so as to keep the volume of said chamber constant during the,injection, and means adapted to act in synchronism with the movement of'said first piston for suddenly releasing'said second piston to permit free increase of the volume of said chamber, whereby the pressure drops suddenly in said pump barrel and stops injection.

3. An injection pump which comprises, in combination, a pump barrel, liquid inlet means con-, nected to said pump barrel, a piston movable in said pump barrel, a spring loaded discharge valve connected with said pump barrel, acylinder in permanent communication with the portion of said pump barrel between said piston and said discharge valve, a piston slidable in said cylinder, so as to form, in said cylinder, a variable volume chamber communicating with said portion of the pump barrel, means for lock ng said second piston with respect to its cylinder so as to keep the volume of said chamber constant during the injection, and adjustable means adapted to act in synchronism with the movement of said first piston for suddenly releasing said second piston to permit free increaseof the nected to said pump barrel, a piston movable in said pump barrel, a spring loaded discharge valve connected with said pump barrel, a cylinder in permanent communication with the portion of said pump barrel between said piston and said discharge valve, a piston slidable in said cylinder, so as to form, in said cylinder. a variable volume chamber communicating with said portion of the pump barrel, means for lock ng said second piston with respect to its cylinder so as to keep the volume of said chamber constant during the injection and means operative by said piston for suddenly releasing said second piston to permit free increaseof the volume of said chamber, whereby the pressure drops suddenly in said pump barrel and stops injection.

5. An injection pump which comprises. in combination, a pump barrel, liquid inlet means connected to said pump barrel, a piston movable in said pump barrel, a spring loaded discharge valve connected with'said pump barrel, 2, cyl nder in permanent communication with the portion of .said pump barrel between said piston and said pump barrel and stops discharge valve, a piston slidable in said cylinder, so as to form, in said cylinder, a variable volume chamber communicating with said portion of the pump barrel, means for locking said second piston with respect to its cylinder so as to keep the volume of said chamber constant during the injection and adjustable means operative by said piston for suddenly releasing said second piston to permit free increaseof the volume of said chamber, whereby the pressure drops suddenly in said pump barrel and stops injection.

6. An injection'pump which comprises, in combination, a pump barrel, liquid inlet means connected to said pump barrel, a piston movable in said pump barrel, a spring loaded discharge valve connected with said pump barrel, a cylinder in permanent communication with the portion of said pump barrel between said piston and said discharge valve, a piston slidable in said cylinder, so as to form, in said cylinder, a variable volume chamber communicating with said portion of the pump barrel, a stop piece adapted to cooperate with said second piston for'fixing it with respect to its cylinder so as to keep the volume of said chamber constant during the injection, said stop piece being retractable ;with respect to said second piston substantially in the direction of the axis'thereof, and means adapted to act in synchronism with the movement of said first piston, and means for suddenly retracting said stop piecet'o release said piston and to permit free increase of the volume of said chamber, whereby the pressure drops suddenly in said pump barrel and stops injection.

bination, a pump barrel, liquid inlet means connected to said pump barrel, a piston movable in said pump barrel, a spring loaded discharge valve connected with said pump barrelya cylinder in permanent communication with the portion of said pump barrel between said piston and said '7. An injection pump-which comprises, in com-v discharge valve, a piston slidable in said cylinder, so as to form, in said cylinder, a variable volume chamber communicating with said portiomof the pump barrel, a stop pieceadapted to cooperate with said second piston for fixing it with respect to its cylinder so as to keep the volume of said chamber constant during the injection, said stop piece being retractable with respect to said second piston, retracting means for moving said stop piece so as to release said second piston and to permit free increase of the volume of said chamber, whereby the pressure drops suddenly in said pump barrel and stops injection and a single cam means for controlling the movement of said second piston and of said retracting means.

8. An injection pump which comprises, in combination, a pump barrel, liquid inlet means connected to said pump barrel, a piston movable in said pump barrel, 9. spring loaded discharge valve connected with said pump barrel, a cylinder in permanent communication with'the portion of said pump barrel between said piston and said discharge valve, a piston slidable in said cylinder, so as to form, in said cylinder, a variable volume chamber communicating with said portion of the pump barrel, abutment means adapted to cooperate with saidsecond piston ior fixing it with respect to its cylinder so as to keep the volume of said chamber constant during the injection, said abutment means being retractable with respect to said second "piston in a direction transverse to the axis thereof, and means adapted to act in synchronism with the movement oi. said first piston for suddenly retracting said abutment means to release said piston and to permit-tree increase of the volume of said chamber, whereby the pressure drops suddenly in said pump barrel and stops injection.

9. An injection pump which comprises, in combination, a pump barrel, liquid inlet means connected to said pump barrel, 9. piston movable in said pump barrel, a spring loaded discharge valve connected with said pump barrel, a cylinder in permanent communication with theportion of said pump barrel between said piston and said discharge valve, 2. piston slidable in said cylinder, so as to form, in said cylinder, a variable volume chamber communicating with said portion of the pump barrel, a stationary sleeve coaxial with said second piston provided with radial holes, abutment balls in said holes adapted to cooperate with said second piston for fixing it with respect to its cylinder so as to keep the volume of said chamber constant during the injection, said balls being retractable with respect to said second piston by radial outward movement in said holes, and a second sleeve surrounding the first and adapted to slide axially with respect thereto in synchronism with the movement of said first piston, provided with recesses adapted to come into register with said holes for suddenly causing said balls to retract into said recesses so as to' release said piston and to permit free increase of the volume of said chamber, whereby the pressure drops suddenly in said pump barrel and stops injection,

10. An injection pump which comprises, in combination, a pump barrel, liquid inlet means connected to said pump barrel, a piston movable in said pump barrel, a spring loaded discharge valve connected with said pump barrel, a cylinder in permanent communication with the portion of said pump barrel between said piston and said discharge valve, a piston slidable in said cylinder, so as to form, in said cylinder, a variable volume chamber communicating with said portion of the pump barrel, an abutment piece adapted to cooperate with said second piston for fixing it with respect to its cylinder so as to keep the volume of said chamber constant during the injection, said abutment means. being retractable with respect to said second piston and a snap action mechanism interposed between a fixed point and said stop piece for holding the latter, for a time, in fixed position with respect to said cylinder and adapted to actin synchronism with the movement of said first piston, for suddenly retracting said abutment piece to release said piston and to permit free increase of the volume of said chamber, whereby the pressure drops suddenly in said pump barrel and stops injection.

11. An injection pump which comprises, in combination, a pumpv barreL'liquid inlet means connected to said pump barrel, a piston movable in said pump barrel, a spring loaded discharge valve connected with said pump barrel, a cylinder in permanent communication with the portion of piece for holding the latter, for a time, fixed position with respect to said cylinder and means carried by said first piston, for snapping said knuckle and causing it suddenly to retract said abutment piece to release said piston and to permit free increase of the volume of said chamber, whereby the pressure drops suddenly in said pump barrel and stops injection.

12. An injecting pump which comprises, in,

combination, a pump barrel, liquid inlet means connected to said pump barrel, a piston movable in said pump barrel, a spring loaded discharge valve connected with said pump barrel, a cylinder inpermanent communication with the portion of said pump barrel between said piston and said discharge valve, a piston slidable in said cylinder, so as to be free to move in said cylinder in response to the movement of the first piston for a portion of its stroke toward the discharge valve,

after the closing of. said inlet means, without the pressure rising in said pump barrel, means for suddenly'stopping this movement of the second mentioned piston whereby the pressure rises suddenly in said pump barrel and said discharge valve opens, to produce injection during another portion of the remainder of said stroke, and means for suddenly releasing said second piston to again permit free movement of said second piston in response to the movement of the first piston still another portion of said stroke, where- JEAN IVHZRCIER. 

